[crac] RFR: 8348867: [CRaC] Simplify CPUFeatures code

[Timofei Pushkin]

Replaces abandoned #112, but the change set is slightly different

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Commit messages:
 - Add missing macro
 - Simplify CPUFeatures code

Changes: https://git.openjdk.org/crac/pull/194/files
  Webrev: https://webrevs.openjdk.org/?repo=crac&pr=194&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348867
  Stats: 123 lines in 1 file changed: 26 ins; 63 del; 34 mod
  Patch: https://git.openjdk.org/crac/pull/194.diff
  Fetch: git fetch https://git.openjdk.org/crac.git pull/194/head:pull/194

PR: https://git.openjdk.org/crac/pull/194